A principal product of the so-called "information age" is that information, at one time difficult to find and retrieve, can be made available instantaneously at a person's finger tips. While the advent of computers helped to bring about the information age, the information age is also expected to fuel further evolution in computer technology. Computer systems of the future will be faster, more compact, ergonomical, and user friendly.
The display continues to be a critical part of the any computer system, displaying anything from typical alphanumerics to multiple windows of information containing graphics, video, as well as interactive menus and control. With the emphasis on multi-media, displays must be larger, have improved contrast and color, and be of higher resolution.
Presently, most displays use Cathode Ray Tube (CRT) technology because it is a mature technology and therefore cost effective. In addition, CRT displays offer good brightness, contrast, colors, resolution, reliability, as well as wide viewing angle. However, CRT displays are big, heavy, and consume considerable power. CRTs also produce x-rays and low-frequency magnetic fields that are believed to cause health hazards. The present trend toward computer portability as indicated by the proliferation of laptops has created requirements in size, weight, and power consumption that CRTs are unable to meet. As such, flat-panel display (FPD) technology is being used instead of CRT technology for laptops, notebooks, etc.
Currently, there are several types of FPD, including passive-matrix liquid crystal displays (LCDs), active-matrix LCDs, AC plasma display panels, AC thin-film electro-luminescent, field-emission displays, vacuum-fluorescent displays, and LEDs. At this time, despite some setbacks, active-matrix LCD is the best performing FPD in terms of color, contrast, and brightness. As advances in LCD technology continue to be made, the size of LCDs continues to grow. Indeed, LCDs of the size of 800.times.600 pixels has begun to replace 640.times.480 LCDs as the industry standard. Even larger size LCDs (e.g., 1024.times.768, 1280.times.1024, etc.) have been made available.
In many ways, the availability of larger LCDs has created new challenges for graphics cards used in controlling video displays. Presently, the Video Graphics Array (VGA) has established itself as the predominant graphics card used in the Personal Computer (PC) family of computers. VGA controllers are being used in PC platforms ranging from laptops to desktops. The current graphics resolution standard for VGA controllers is 640.times.480 pixels. Given this resolution standard, large monitors (e.g., 800.times.600 pixels, 1024.times.768 pixels, and 1,280.times.1,024 pixels) that are becoming available pose challenges to the current VGA graphics controllers.
While the challenges presented by large screens affect both CRTs and FPDs, they have a more direct effect on FPDs, more particularly LCDs. The reason is that FPDs have a fixed number of pixels and lines that are lighted when the monitor is in use regardless of the size of the graphics displayed on the screen. As such, when the LCD screen size is larger than the VGA standard graphics resolution of 640.times.480 pixels, the display on the screen does not utilize the full screen area available. Additionally, the display would not be centered on the LCD screen.
On the other hand, CRTs have more flexibility than FPDs. Among other things, CRTs have the ability to adjust the size of the pixels to fill the screen. That is, while the graphics resolution remains at 640.times.480 pixels, the size of pixels is enlarged so that the full screen area is utilized. However, since the same number of pixels are now spread over a larger square area, the dot-per-inch (DPI) density of display decreases resulting in a degradation in sharpness.
While there exist other graphics card formats (e.g., Super VGA, XGA) that are designed for larger graphics resolution, they remain prohibitively expensive because they have not yet gained acceptance as industry standards. For this reason, what is needed is a VGA controller card with a standard resolution format of 640.times.480 pixels that is capable of duplicating the number of pixels to fill the full screen area of a large FPD (e.g., 800.times.600 pixels resolution). More specifically, what is needed is a VGA controller card with the capability to expand both VGA graphics and text mode displays. At the minimum, such controller has the capability to accommodate the following text mode resolutions: 640.times.200, 640.times.350, 640.times.400, 720.times.350, and 720.times.400.